[RFC PATCH 4/8] rust: drm: implement `AsRef` for DRM device

[Danilo Krummrich <dakr@xxxxxxxxxx>]

Implement `AsRef<device::Device>` for `drm::device::Device` such that
`dev_*` print macros can be used conveniently.

Signed-off-by: Danilo Krummrich <dakr@xxxxxxxxxx>
---
 rust/kernel/drm/device.rs | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/rust/kernel/drm/device.rs b/rust/kernel/drm/device.rs
index f72bab8dd42d..aef947893dab 100644
--- a/rust/kernel/drm/device.rs
+++ b/rust/kernel/drm/device.rs
@@ -79,6 +79,14 @@ unsafe fn dec_ref(obj: NonNull<Self>) {
     }
 }
 
+impl<T: drm::drv::Driver> AsRef<device::Device> for Device<T> {
+    fn as_ref(&self) -> &device::Device {
+        // SAFETY: `bindings::drm_device::dev` is valid as long as the DRM device itself is valid,
+        // which is guaranteed by the type invariant.
+        unsafe { device::Device::as_ref((*self.as_raw()).dev) }
+    }
+}
+
 // SAFETY: `Device` only holds a pointer to a C device, which is safe to be used from any thread.
 unsafe impl<T: drm::drv::Driver> Send for Device<T> {}
 
-- 
2.45.1